A number of compounds are being prepared which can potentially inhibit important metabolic pathways. We will investigate the effect of this inhibition upon the growth of tissue cells. Compounds currently under investigation are gabaculine analogs, fluoro-aspartate and other Beta-fluorinated amino acids. Method of delivering drugs more effectively and cells specifically are being studied. This includes covalent attachment of drugs to hormones and to liposomes which are modified so as to specifically interact with certain cell types. It has been found that 5'-deoxyadenosine is toxic to certain cell types and non-toxic to others. The basis for this toxicity and also the drug resistance are being investigated.